Water treatment mud decanting tank

ABSTRACT

A mud decanting tank for water cold treatment with lime including a substantially cylindrical tank, housing a concentric pipe opened at its ends, and a second vertical eccentric pipe engaged at its top portion with said first pipe by a channel; and at its lower end said eccentric pipe being engaged with a third horizontal pipe located slightly spaced below the open lower end of the first mentioned vertical pipe; the third horizontal pipe including at its lower portion a bore; said three pipes forming a continuous recycling pipeline which draw out the muds by suction from the bottom of said tank by means of stirrers and removers mounted in a pair of parallelly spaced shafts housed respectively in each one of said vertical pipes, said shafts being driven in the same direction by a prime mover.

Primary Examiner.lohn Adee Assistant Examiner-Robert H. SpitzerAttorney, Agent, or Firm-Ladas, Parry, Von Gehr, Goldsmith & Deschamps[57] ABSTRACT A mud decanting tank for water cold treatment with m .m Mfiw a 3 E m m D D M U 8% M M a E BMW M w M T m A HEW E ai R JCC T u E mm AA V WT .m

[22] Filed: Sept. 20,1972 lime including a substantially cylindricaltank, housing [2]] a concentric pipe opened at its ends, and a secondAppl. No.: 290,688

. vertical eccentric pipe engaged at its top portion with "said firstpipe by a channel; and at its lower end said eccentric pipe beingengaged with a third horizontal pipe located slightly spaced below theopen lower end 94 H Q1 .02 m MB 0 1 2 of the first mentioned verticalpipe; the third horizontal pipe including at its lower portion a bore;said three pipes forming a continuous recycling pipeline which draw outthe muds by suction from the bottom of said tank by means of stirrersand removers mounted in a pair of parallelly spaced shafts housedrespectively in each one of said vertical pipes, said shafts beingdriven in the same direction by a prime mover.

[58] Field of Search....... 210/60, 62, 197, 208, 219, 210/319, 523

References Cited UNITED STATES PATENTS 210/197 X 210/208 5/1944 Green210/208 X 3/1943 Green 210/208 X 8 Claims, 3 Drawing Figures 3,397,788Duff et 2,429,315 2,348,122 2,314,977

PATENTEB 74 SHEET 1 (IF 3 :fig

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PATENTEU 51374 SHEU 2 0F 3 WATER TREATMENT MUD DECANTENG TANK BACKGROUNDOF THE INVENTION The remarkable industrial development has increased theneed for soft or treated water which is used in boilers, industrialplants and the like.

The water, in its natural condition, takes up oxygen, carbon dioxide,nitrogen, dust and other impurities from air. Said elements render thewater more or less solvent for earth minerals. This contamination may besubsequently increased by acids resulting from falling organic matter,industrial waste and sewage. The materials contained in the water can beclassified as dissolved or suspended. in the term dissolved substances,are included calcium bicarbonate, as well as magnesium and sodiumbicarbonate, that is: Ca (HCO Mg (HCO and Na HCO calcium, magnesium andsodium sulphates. Ca 80,, Mg 50,, Na S calcium and magnesium nitrates Ca(N09 and Mg (NO calcium, magnesium and sodium chorides CaCl Mg Cl andNaCl, iron oxide Fe O silicon dioxide SiO industrial wastes and gasessuch as oxygen 0 and carbon dioxide CO The suspended materials comprisemud, sand, material of vegetal origon and industrial waste.

The water impurities produce in boilers and power plants damagingeffects such as reduction of the amount of heat transfer due to scalingon the water heating surfaces; corroding of the steel of boilers thusmaking it brittle; cost increases for cleaning, repairing, inspection,maintenance and preservation of the equipment; heat losses due to theneed of frequent water purges; and enconomy losses in steam equipmentcaused by the dirty steam.

The term water hardness is used to indicate the tendency of water toform scales and crusts that will depend on the nature of the impuritiescarried by the water. This water hardness can be rated as hardness withcabonates or hardness without carbonates. The amount of the scaleforming materials can be expressed in terms of ppm equivalent to calciumcarbonate (Ca- CO);,. The hard waters vary in a hardness range from lessthan 10 ppm to more than 1800 ppm. Such high hardness in the water makesit unsuitable for industrial purposes.

The water treatment for removing or reducing impurities must be carriedout only after a suitable analysis of the water to be treated has beeneffected. There is no suitable process or treatment for all types ofwater, each case must be considered individually. Among the processesemployed for water treatment, mention may be made of the following:waste removal by means of moving or stationary screens; filtering; theseparation of mud and residues in settling reservoirs; heating;evaporation or distillation by aeration; treatment with lime; treatmentwith sodium carbonate; treatment with a combination of lime and sodiumcarbonate, with lime and barium, with trisodium phosphate, withcoagulants and with zeolite softeners. The diversified processes are notcarried out in the same manner, some of them are continuous and othersare of the batch type.

SUMMARY OF THE lNVENTION The process of the present invention is the onerelated to the water treatment, called a cold treatment with lime.

This process is suitable for the water hardness with carbonates, whereinthe lime used is in its hydrated form, Ca (Oi-D The alkalinity islowered and the carbonic acid in the water, CO is eliminated, whether inits free state or in combination with bicarbonate, and relativelyinsoluble precipitates of calcium carbonate and magnesium hydroxide areformed. The respective reactions are:

CO Ca(OH) CaCO H O Ca(HCO Ca(OH ZCaCO 2H O ZNaHCO Ca(OH) caco Na CO 211x0 The process is carried out in a most suitable manner in large tankswherein the soft water can be decanted and the muds can be removed fromthe processing plant.

Heretofore the tanks used to carry out this type of process haveemployed means that prevent a complete reaction of the chemicals andwherein the proportioning or metering of the reagents cannot be adjustedor controlled at a fast rate and the homogeneity of the mixture is notoptimum.

The equipment used heretofore is characterized in that it includes asubstantially cylindrical tank, inside of which and concentrically tosame is located a second cylinder in the vertical axis of which, inturn, is located a shaft that drives a stirrer to recycle the muds andthe chemicals which, due to a tapered cone formed at the bottom of thetank, shall be deposited, depending on their density, in successivelayers leaving the soft or processed water on top, from which it isemoved for later use.

It is an object of the present invention to provide a mud decanting tankincluding a recycling of the muds and chemicals promoting a morecomplete reaction of same and affording the proper proportioning of thereagents, thereby obtaining an homogeneous mixture.

Said mud decanting tank for the water cold treatment with lime of thepresent invention comprises a substantially cylindrical tank having aninteriorly tapered bottom, and a concentric pipe housing a centralvertical shaft driving a stirrer and a coaxial remover driven by meansof a suitable prime mover and comprising manifolds or overflows locatedat a determined level for drawing out the processed water and areservoir for chemicals supplying and metering. There is also includedtherein a second eccentric inner pipe having also a central verticalshaft that drives a stirrer and remover by means of a suitable primemover engaged or coupled to the top of the central pipe. Said eccentricpipe, at its lower end, leads to a third horizontal pipe locatedslightly below the lower outlet of the first concentric pipe; thehorizontal pipe being closed at its ends and including a mouth or borein a lower side portion, concentric to the tank.

The distribution of said inner piping provides, by means of thestirrers, a continuous recycling of the muds and chemicals, therebyattaining the beneficial effects above mentioned.

These and other objects that are realized by the practice of thisinvention will be better understood upon reading the followingdescription in which reference is made to the enclosed drawing and ofthe preferred embodiment of the same,

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1, is a side elevational viewwith a partial section, showing the decanting tank of the presentinvention.

FIG. 2, is a top plan view of the decanting tank of the presentinvention.

FIG. 3, is a side elevational view with a partial section, at 90 fromthe view shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The mud decanting tank 1 1, forwater cold treatment with lime of the present invention includes acylindrical tank 12, substantially vertical with its inner bottom 13,being tapered to promote decantation of the impurities, and includes anupright concentric pipe 15, having a slightly flared mouth or outlet 16,that houses a concentric vertical shaft 17, that drives a stirrer 18,and a bar remover 19, by means of a suitable prime mover, such as areducing motor 20, through bands 21 and pulleys 22, supported on top ofsaid tank, at a structure 23 and including a second eccentric verticalpipe 24, with its side wall substantially tangent to the tank wall.

The eccentric pipe is engaged at its lower end to a third horizontalpipe 25, havingits end closed by a plate 26 and the top of which isslightly spaced below the outlet 16 of pipe 15. The horizontal pipeincludes at the lower portion of its side wall a mouth 27 from which themuds are drawn out by suction from the bottom of said tank.

At the top, both vertical pipes are joined by means of a channel 31.

The muds are drawn out by suction from the bottom of the tank throughmouth 27 by means of stirrer 18 located in the horizontal pipe 25 fromwhich, by means of the turbine stirrer 29, said muds are cycled throughthe vertical pipe 24, passing through the channel 31 and down theconcentric pipe 15 to the bottom of the tank, wherein the recycling isonce more initiated so that, as previously noted, a promotion of a morecomplete reaction of the muds and chemicals is effected and thusaffording a better control and metering of the reagents that are fed totank 32 and by means of a conduit 33 are introduced into the lower endof pipe 24, to be mixed with the muds.

In order to avoid unwanted buildup of the muds, the

bar removers l9 and are respectively included in the lower part ofshafts l7 and 28. The tank 12 includes at its lower end a compartment 34formed by a cylindrical wall intersecting the tank wall 12 and having anouter purging conduit 35 for draining the settled material.

At a certain level, manifolds or overflows 36 are included in order towithdraw the processed and clarified water from the tank through piping37 that communicates with the outlet pipe 38.

Even though, the above description has been made in relation to aspecific embodiment of the invention, it is to be understood by thoseskilled in the art that the above mentioned or any other change in formand detail, should be considered as being comprised within the truespirit and scope of same.

I claim:

1. A mud decanting tank for water cold treatment with lime including asubstantially cylindrical tank with an inner tapered bottom and an innerconcentric pipe open at its upper and lower ends and disposedsubstantially vertical housing a central vertical shaft that drives acoaxial stirrer and bar remover by means of a suitable prime mover,overflow means for the processed water, a reservoir for meteringreagents and a draining means for settled solids, wherein said tankhaving a second eccentric inner pipe closed at its lower end including acentral vertical shaft that drives a second stirrer and bar remover bymeans of a suitable prime mover, said second pipe being in communicationwith the top of the concentric pipe by means of a channel, saideccentric pipe being also communicated at its lower side wall to a thirdhorizontal pipe located slightly spaced below the open lower end of thevertical concentric pipe, said horizontal pipe being closed at its endand including a bore leading downwardly concentric with the tank at alower side portion of the pipe for drawing out the mud by suction, andwherein said stirrer of said central shaft is located in said horizontalpipe above said mud suction bore and said first and second bar removersare located at the lower end of their respective shafts.

2. A mud decanting tank according to claim 1, wherein the stirrers areof the turbine type.

3. A mud decanting tank according to claim 1, wherein said open lowerend of said inner concentric pipe located slightly above said thirdhorizontal pipe is flared.

4. A mud decanting tank according to claim 1, wherein said shafts aredriven in the same direction by a reducing motor located on top of thetank by means of bands and pulleys.

5. A mud decanting tank according to claim 1, wherein the eccentric pipehas its side wall substantially tangent to the tank wall.

6. A mud decanting tank according to claim 1, wherein the cross sectionof said concentric and eccentric pipes is substantially circular.

7. A mud decanting tank according to claim I, wherein the reagentreservoir includes a conduit communicating same with the horizontalpipe.

8. A mud decanting tank according to claim 1, wherein the channeljoining both concentric and eccentric pipes has its side walls tangentto the walls of the pipes.

1. A mud decanting tank for water cold treatment with lime including asubstantially cylindrical tank with an inner tapered bottom and an innerconcentric pipe open at its upper and lower ends and disposedsubstantially vertical housing a central vertical shaft that drives acoaxial stirrer and bar remover by means of a suitable prime mover,overflow means for the processed water, a reservoir for meteringreagents and a draining means for settled solids, wherein said tankhaving a second eccentric inner pipe closed at its lower end including acentral vertical shaft that drives a second stirrer and bar remover bymeans of a suitable prime mover, said second pipe being in communicationwith the top of the concentric pipe by means of a channel, saideccentric pipe being also communicated at its lower side wall to a thirdhorizontal pipe located slightly spaced below the open lower end of theVertical concentric pipe, said horizontal pipe being closed at its endand including a bore leading downwardly concentric with the tank at alower side portion of the pipe for drawing out the mud by suction, andwherein said stirrer of said central shaft is located in said horizontalpipe above said mud suction bore and said first and second bar removersare located at the lower end of their respective shafts.
 2. A muddecanting tank according to claim 1, wherein the stirrers are of theturbine type.
 3. A mud decanting tank according to claim 1, wherein saidopen lower end of said inner concentric pipe located slightly above saidthird horizontal pipe is flared.
 4. A mud decanting tank according toclaim 1, wherein said shafts are driven in the same direction by areducing motor located on top of the tank by means of bands and pulleys.5. A mud decanting tank according to claim 1, wherein the eccentric pipehas its side wall substantially tangent to the tank wall.
 6. A muddecanting tank according to claim 1, wherein the cross section of saidconcentric and eccentric pipes is substantially circular.
 7. A muddecanting tank according to claim 1, wherein the reagent reservoirincludes a conduit communicating same with the horizontal pipe.
 8. A muddecanting tank according to claim 1, wherein the channel joining bothconcentric and eccentric pipes has its side walls tangent to the wallsof the pipes.